v-Triazolo[4,5-d]pyrimidines (8-azapurines). Part XIII. Reaction of 8-azapurines with bifunctional nucleophiles

Abstract

8-Azapurine and its 2-oxo- and 2-thioxo-derivatives were cleaved by 1,1-dimethylhydrazine to yield 4-dimethylhydrazonomethylamino-(7a), 4-ureido-(5a), and 4-thioureido-(5b) 1,2,3-triazole-5-carbaldehyde dimethylhydrazone, respectively, and by hydrazine to give 4-amino-(9a), 4-ureido-(9b), and 4-thioureido-(9c) 1,2,3-triazole-5-carbaldehyde azine, respectively. 2-Amino-8-azapurine gave 4-hydrazonomethylamino-1,2,3-triazole-5-carbaldehyde hydrazone (7d).

With hydroxylamine, 8-azapurine and its 2-amino and 2-thioxo-derivatives yielded, respectively, 4-hydroxyiminomethylamino-(7b), 4-diaminomethyleneamino-(4a), and 4-thioureido-(5c) 1,2,3-triazole-5-carbaldehyde oxime, whereas the reaction with 8-azapurin-2(3H)-one stopped at the addition product 1,6-dihydro-6-hydroxyamino-8-azapurin-2(3H)-one (3a). Similarly 8-azapurine and methoxyamine yielded 5-methoxyiminomethyl-4-methoxyiminomethylamino-1,2,3-triazole (7c), whereas its 2-oxo-derivative gave 1,6-dihydro-6-methoxyamino-8-azapurin-2(3H)-one (3b).

¹ H N.m.r. and u.v. spectra, and some pK_a values, are reported; their bearing upon the structures of the products and the reaction mechanisms is discussed.